You have to define "crazies" though. When you buy a gun from a licensed FFL, or reside in a state where a background check is required even for private sales you have to fill out a Form 4473. Form 4473, Section 21, subsection F asks the following:
So, theoretically.. This base is covered, as long as the person filling out the form is truthful. Of course, this wouldn't apply to private sales between two parties where a background check through an authorized FFL dealer is not required (which would trigger use of the 4473), and wouldn't account for all the "crazies" that are out there that aren't yet on the radar. People could be bat$&%^ crazy and never been hospitalized/committed for it, been picked up by the law and processed, etc.. However, the same could be said for privately selling a gun to a felon. It's not like they wear a name tag with the designation on it. LOL Different states have different laws, so you have to know the law for the state that you live it. But, as an example.. Where I live in Arkansas, the law only states the following:
That's pretty much it. So, as long as I don't know or reasonably believe someone to either (A) Be a convicted felon or (B) would answer "yes" to any of the other question in section 21 of Form 4473 then I can sell privately to them and nobody would be the wiser. No background check and/or FLL transfer. What they do with it after that is out of my control, but you can bet your behind that even though a background check/transfer by FFL isn't required in Arkansas, I still get a Bill of Sale with all pertinent information and signature of the buyer. Just in case that gun is used to commit a crime. If I bought it new, there is a 4473 out there with the make/model/serial number of that weapon and my name on it, and I want to have documentation to prove that I no longer own that weapon.
While I don't necessarily disagree with what you are saying here, but it treads awfully close to "Red Flag" laws which I am 110% and inequivically against. If there is documented proof of someone making threats (FB, Email, Online, etc..) or someone is willing to be sworn in and testify in a court of law that they heard someone making these types of claims, then absolutely.. they should be looked in to. However, under "Red Flag" legislation anyone that "thinks that Joe Blow down the street may do harm to themselves or others" because another "Joe Blow" says so can have their guns taken away and possibly arrested. That's no bueno. This would likely cause legal expenses for the accused to prove their innocence and that they are not a threat to themselves or anyone else and get their property back. Just because someone said something that might not be true. I believe that any form of "Red Flag" legislation that may be passed, needs to included penalties for the accuser if it is found that there was no basis for the accusation. This would include allowing the person accused to sue for libel, defamation of character, slander, legal fees, compensatory damages, etc.. Effectively throw the book at them, to make sure that if you're going to throw somebody under that bus.. you better be able to back it up.
Anyway, just my two pennies.